Re: [PATCH] clocksource/drivers/timer-mediatek: optimize systimer irq clear flow on Mediatek Socs
From: Daniel Lezcano <hidden>
Date: 2021-03-22 10:11:53
Also in:
linux-arm-kernel, lkml
On 02/03/2021 08:28, Fengquan Chen wrote:
1)ensure systimer is enabled before clear and disable interrupt, which only for systimer in Mediatek Socs. 2)clear any pending timer-irq when shutdown to keep suspend flow clean, when use systimer as tick-broadcast timer Change-Id: Ia3eda83324af2fdaf5cbb3569a9bf020a11f8009
Remove the above. Add a Fixes tag.
quoted hunk ↗ jump to hunk
Signed-off-by: Fengquan Chen <redacted> --- drivers/clocksource/timer-mediatek.c | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/drivers/clocksource/timer-mediatek.c b/drivers/clocksource/timer-mediatek.c index 9318edc..9f1f095dc 100644 --- a/drivers/clocksource/timer-mediatek.c +++ b/drivers/clocksource/timer-mediatek.c@@ -75,6 +75,7 @@ static void mtk_syst_ack_irq(struct timer_of *to) { /* Clear and disable interrupt */ + writel(SYST_CON_EN, SYST_CON_REG(to));
SYST_CON_EN is set below, why do you have to do it before? Is that a hw bug ? It is confusing what the description of the SYST_CON_EN says: /* * SYST_CON_EN: Clock enable. Shall be set to * - Start timer countdown. * - Allow timeout ticks being updated. * - Allow changing interrupt functions. What means "interrupt functions" ? Does writing writel(SYST_CON_EN, SYST_CON_REG(to)) before SYST_CON_IRQ_CLR allows to clear the interrupt flag? Can you explain how the timer works regarding this part? It sounds to me a bit strange. * * SYST_CON_IRQ_EN: Set to allow interrupt. * * SYST_CON_IRQ_CLR: Set to clear interrupt. */
quoted hunk ↗ jump to hunk
writel(SYST_CON_IRQ_CLR | SYST_CON_EN, SYST_CON_REG(to)); }@@ -111,6 +112,9 @@ static int mtk_syst_clkevt_next_event(unsigned long ticks, static int mtk_syst_clkevt_shutdown(struct clock_event_device *clkevt) { + /* Clear any irq */ + mtk_syst_ack_irq(to_timer_of(clkevt)); + /* Disable timer */ writel(0, SYST_CON_REG(to_timer_of(clkevt)));
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